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    <p><a class='wikilink' href='Introduction.html'>The PRISM Language</a> /
</p><h1>Model Type</h1>

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<p>As mentioned above, the PRISM language can be used to describe several types of probabilistic models:
DTMCs, CTMCs, MDPs and PTAs.
To indicate which type is being described, a PRISM model should include one of the keywords
<code><strong>dtmc</strong></code>, <code><strong>ctmc</strong></code>, <code><strong>mdp</strong></code> or <code><strong>pta</strong></code>.
This is typically at the very start of the file,
but can actually occur anywhere in the file (except inside modules and other declarations).
If no such model type declaration is included, the model is by default assumed to be an MDP.
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<p class='vspace'><strong>Note:</strong> As mentioned earlier, PRISM also supports probabilistic automata (PAs) [<a class='wikilink' href='../Main/References.html#Seg95'>Seg95</a>], but (mis)uses the terminology Markov decision process (MDP) for this model.
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<p class='vspace'><strong>Note:</strong> For compatibility with old versions of PRISM,
the keywords <code><strong>probabilistic</strong></code>, <code><strong>stochastic</strong></code> and <code><strong>nondeterministic</strong></code>
can be used as alternatives for <code><strong>dtmc</strong></code>, <code><strong>ctmc</strong></code> and <code><strong>mdp</strong></code>, respectively.
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<h3><a class='wikilink' href='../Main/Welcome.html'>PRISM Manual</a></h3>
<p><strong><a class='wikilink' href='Introduction.html'>The PRISM Language</a></strong>
</p><ul><li><a class='wikilink' href='Introduction.html'>Introduction</a>
</li><li><a class='wikilink' href='Example1.html'>Example 1</a>
</li><li><a class='selflink' href='ModelType.html'>Model Type</a>
</li><li><a class='wikilink' href='ModulesAndVariables.html'>Modules And Variables</a>
</li><li><a class='wikilink' href='Commands.html'>Commands</a>
</li><li><a class='wikilink' href='ParallelComposition.html'>Parallel Composition</a>
</li><li><a class='wikilink' href='LocalNondeterminism.html'>Local Nondeterminism</a>
</li><li><a class='wikilink' href='CTMCs.html'>CTMCs</a>
</li><li><a class='wikilink' href='Example2.html'>Example 2</a>
</li><li><a class='wikilink' href='Constants.html'>Constants</a>
</li><li><a class='wikilink' href='Expressions.html'>Expressions</a>
</li><li><a class='wikilink' href='Synchronisation.html'>Synchronisation</a>
</li><li><a class='wikilink' href='ModuleRenaming.html'>Module Renaming</a>
</li><li><a class='wikilink' href='MultipleInitialStates.html'>Multiple Initial States</a>
</li><li><a class='wikilink' href='GlobalVariables.html'>Global Variables</a>
</li><li><a class='wikilink' href='FormulasAndLabels.html'>Formulas And Labels</a>
</li><li><a class='wikilink' href='PTAs.html'>PTAs</a>
</li><li><a class='wikilink' href='CostsAndRewards.html'>Costs And Rewards</a>
</li><li><a class='wikilink' href='ProcessAlgebraOperators.html'>Process Algebra Operators</a>
</li><li><a class='wikilink' href='PRISMModelFiles.html'>PRISM Model Files</a>
</li></ul><p>[ <a class='wikilink' href='AllOnOnePage.html'>View all</a> ]
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